Why didn't crossbows have longer powerstrokes?

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When you look at medieval crossbows you can see that they have a way higher draw-weight then their bow counterparts. Because of the short powerstroke a crossbow can't transfer all this energy to the bolts used. Making crossbows have a lower draw-weight to power than a bow. My question here is, why didn't people back in the day a longer powerstroke? If you give crossbow like 1000 pounds of draw-weight and powerstroke of 30 inches you could easily pierce late-medieval armor with that. Below you can see the math which is used to measure the force. And a couple of examples of different crossbows.

Heaviest standard 8 stone Han crossbow power = 516 lbs draw weight * ~19 inches powerstroke/2 = 4902 inch lbs
Heaviest Medieval crossbow found from Gallway = 1200 lbs draw weight * 7 inches powerstroke/2 = 4200 inch lbs
Typical 6 stone strength Han crossbow's power = 387 lbs draw weight * ~19 inches powerstroke/2 = 3676.5 inch pounds
Heaviest longbow ever found, within Mary Rose = 180 lbs draw weight * ~20 inches powerstroke/2 = 1800 inch pounds
English heaviest battlefield use longbow power = 150 lbs draw weight * ~20 inches powerstroke/2 = 1500 inch pounds
Imaginary crossbow= 1000 lbs draw weight * 30 inches powerstroke/2 = 15000 inch pounds of force( which is op as f**k)

It is important to reliably hit the target. Your reaction to a weapon varies depending on the probability of someone being able to deliver a "kill shot."

That sounds reasonable. Longbows have a better accuracy at longer ranges than a crossbow. And I think the only logical explanation for this is either the ammunition or the longer power stroke. If I used the power stroke of a longbow and put it on the heaviest medieval crossbow the weight would increase due to extra length. I however do get a great deal of brutal stopping power in return.( 12000 pounds)

Some ancient cultures did have overgrown stationary crossbows mounted on fortress walls with systems of ratchets and cranks that enabled you to pull a much bigger bow (and fire a bigger arrow) than a human could pull with his arms alone. These were more powerful than the normal portable crossbows (and longbows) carried by either mounted warriors, or by foot soldiers, who moved about the battlefield. How much more powerful I dont know.

Portability is also an issue. Having a giant powerstroke makes carrying the weapon inpractical.
Then there is the matter of reloading: often, a squire would reload the weapon and swap it with the weapon that was just fired (the archer would have 2 bows: one loaded, one that is getting loaded). The bigger the weapon, the more annoying it becomes to exchange them.

You mean ballistas? You can see that in ancient China( during Han Dynasty) they used crossbows with a lower draw weight but a longer powerstroke. Making it easier to pull the string but you get the same or more power out of it. Some medieval crossbows did have a windlass to pull back the massive draw weight. I think the reason why they didn't have longer powerstroke has more to do with material. For heavier draw weights they'd use a steel bow instead of a wooden one. I think if you make the bow to long and put a decent draw weight on it the metal might bend out of shape.

That seems like a good point. But you don't necessarily need a bigger crossbow you can put the latch further backwards. Like this.

Instead of this

That existed too. Siege engines of various kinds were devised to throw big rocks AT fortress walls. Some (like trebeauche and catapaults used balanced wieghts, and some, like ballistas, were overgrown crossbows). But someone like Archemedes (or Ptolemy?) designed one just to shoot oversized arrows, and to do so FROM the fortress walls down at the guys laying siege to you. I saw it on a TV show.Tried, but couldnt track it down on the Net for this thread.

The real question here is ,could you kebab someone in full plate armor with a ballista?

The Roman scorpion ballista could throw a bolt 400 meters and pierce armor.

For accuracy there was nothing that could match it until rifled firearms.